Adjacent to Himeji castle but a 5min walk around the wall is Kokoen Garden. You can buy combo entry tickets to the castle and garden, and the reason is that if you didn’t have the ticket you’d be so tired after walking the castle you’d just go home. I would have appreciated a shortcut from the castle grounds.
It turned out to be quite nice. From the entrance and the map they give you it would appear to be a small garden, but in fact it took us over an hour to walk through it all. The garden was split into many walled sections, and each section was landscaped in a different style and had a unique feel to it.